This part of ISO/IEC13250 specifies a data model of Topic Maps. It defines the abstract structure of Topic Maps, using the information set formalism, and to some extent their interpretation, using prose. The rules for merging in Topic Maps are also defined, as are some fundamental subject identifiers.

The purpose of the data model is to define the interpretation of the Topic Maps interchange syntaxes, and to serve as a foundation for the definition of supporting standards for canonicalization, querying, constraints, and so on. All of these standards fall outside the scope of this part of ISO/IEC13250.